I think this is bad for Lukashenko. The more the EU sanctions Belarus, the more Belarus has to rely on Russia. But the more Belarus has to rely on Russia, the greater Russia's power over Belarus, and the greater the likelihood that Belarus turns into a Russian puppet state in which all the real power and real decisions are being made in Moscow. That outcome threatens to deprive Lukashenko of real power and turn him into a mere figurehead.
He already relies on Russian roubles to keep his repression apparatus running. Fortunately Kremlin's money only cover their paychecks for a few months. When they stop flowing, the Belarussian nomenclature will try to find other means of financing thieir lifestyles. The possible outcomes are either are the Crimean or the Ukraine scenario.